A throttle apparatus is known as a composite product. The throttle apparatus includes a throttle body as the first molding part and a throttle valve as the second molding part. The throttle body supports the throttle valve via a throttle shaft.
JP-5-141540A (U.S. Pat. No. 5,304,336, U.S. Pat. No. 5,421,718) shows a manufacturing method of a throttle apparatus, in which after the first molding part is molded, the second molding part is molded using the first molding part as a part of molding die. The fist molding part is held by the molding die to mold the second molding part. After cooling and solidifying the products, the first and the second molding parts may be freely deformed so that an accuracy of the product is deteriorated. Especially, in molding the throttle valve by the above method, a clearance between the throttle valve and the throttle body is hardly maintained at a predetermined value. Thus, when the throttle valve is positioned at a full close position, an amount of air passing through the throttle valve disperses in each product.